An antenna is mounted at a moving object to receive and transmit a signal from and to a satellite. The antenna mounted at the moving object is controlled to track a target satellite while the moving object is moving. Since the antenna is vibrated by the motion of the moving object, the motion of the moving object is compensated to accurately control the antenna.
As conventional technology for compensating the motion of the moving object, a stabilized antenna system was introduced in U.S. Pat. No. 5,359,337. The conventional stabilized antenna system has an X1-Y-X2 mount structure having three axes, an X1 axis, a Y axis, and an X2 axis. The X1 axis is disposed in parallel to the moving direction of a moving object. The Y axis is disposed vertically to the X1 axis and moves with the X1 axis as a center when the X1 axis rotates. The X2 axis is disposed vertically to the Y axis and moves with the Y axis as a center when the Y axis rotates. Herein, the X2 axis is an electronic control axis that changes the directivity of neighbor antenna, compensates roll elements related to the rolling of the moving object by the rotation of X1 axis, and compensates pitch element related to the pitching of the moving object by the rotation of the Y axis and X2 axis.
As another conventional technology, a three-axis pedestal was introduced in U.S. Pat. No. 5,419,521. The conventional three-axis pedestal is suitable for mounting on a moving structure to provide a unit for obtaining rotational stabilization of an antenna about three mutually perpendicular axes. The pedestal includes a spindle unit, a cantilevered structural member, a pair of spaced apart co-axial bearings, a shaft, a structural beam and a structural unit. The centerline of the spindle unit defines a first pivot axis, and the spindle unit is rigidly attached to the moving structure. The cantilevered structural member includes one end mounted for pivoting motion about the first pivot axis of the spindle unit. The pair of spaced apart co-axial bearings is mounted on the other end of the cantilevered member so that the centerlines thereof define a second pivot axis perpendicular to and intersecting the first pivot axis. The bearings are located on the cantilevered member close to an upward extension of the first axis. The shaft is mounted in the pair of bearings for pivot motion about said second pivot axis. The structural beam is rigidly attached to the shaft. The beam carries a journal at each end thereof so that the centerlines of the journals define a third pivot axis. The third axis is perpendicular to the second pivot axis and nominally intersected the intersection point of the first and second pivot axes. The structural unit is mounted for pivot motion about said third pivot axis. The structural unit is rigidly attached to and supports the object for orbital motion about the common intersection point of each of the first, second and third axes.
However, the conventional pedestal apparatuses are not suitable for a moving object having a wide moving range. Also, it is not easy to control for stabilizing the attitude of a satellite tracking antenna, and it requests a high manufacturing cost.